By Chelsea Henderson, republicEn.org
The Department of Defense no longer considers climate change a national security threat, as flag officers and national security specialists have warned it to be for nearly two decades. That’s bad news not only for Florida and the eight military bases called out in a 2019 Department of Defense report as being vulnerable to climate risks, but for the U.S. Armed Forces serving both at home and abroad.
Before he was embroiled in a classified information breach over the communications app Signal, Defense Secretary Pete Hegseth tweeted: “The @DeptofDefense does not do climate change crap. We do training and warfighting.” His spokesperson likewise avowed that “climate zealotry and other woke chimeras of the Left” were not part of the department’s mission.
The refusal to acknowledge climate change as a tangible threat didn’t stop there. For the first time in over a decade, the U.S. Intelligence Community’s annual threat assessment does not include climate change as a global threat.

Considered a “threat multiplier” by the military and CIA alike, climate change can have a destabilizing effect, exacerbating droughts, stoking resource wars and leading to humanitarian crises and mass migration of people. But the current administration — the only GOP-led executive branch in history to reject climate science — seems to think that by eliminating certain words from the federal government lexicon, they can ignore the problem.
Two prominent Republican figures on the Senate Armed Services Committee are likely rolling over in their graves.
U.S. Sen. John McCain — the naval officer and former prisoner of war who served his state of Arizona for more than 30 years and was the GOP nominee for president in 2008 — made solving climate change one of his signature issues. Crossing his own party at a time when climate denialism was on the rise, he even included the issue in a presidential campaign ad, declaring that climate change is “not just a greenhouse gas issue, it’s a national security issue.”
McCain fought hard with his signature maverick energy to try to sway his colleagues on both sides of the aisle to support economy-wide climate legislation. Both times the Senate voted on the bill he co-wrote with Sen. Joe Lieberman, the measure failed. But driven by his belief in getting his peers on the record, he didn’t back down from the fight.
“Global warming presents a test of foresight, of political courage and of the unselfish concern that one generation owes to the next,” McCain said in a 2008 speech. “We need to think straight about the dangers ahead, and to meet the problem with all the resources of human ingenuity at our disposal.”
Meanwhile, in the last of his 30 years serving the commonwealth of Virginia, Republican Sen. John Warner, another war veteran who long served on both the Senate Armed Services Committee and the Senate Environment and Public Works Committee, was so moved by testimony from retired flag officers warning of the threats climate change posed to national security that he felt compelled to write a climate change bill akin to McCain’s and to continue to work on the issue in the private sector after he retired from public service. He was also instrumental in requiring the Pentagon to consider climate change as a national security risk in the Quadrennial Defense Review.

Not acknowledging climate change isn’t going to make the hurricane season magically less ominous in the future. Eliminating references to climate change isn’t going to stop sea level rise at Naval Station Norfolk, the world’s largest naval base, which has seen an 18-inch rise in sea level since 1927.
“These are some of the Navy’s most critical assets,” Commander Kendall Chapman, the shipyard’s resident officer in charge of construction, said to the Wall Street Journal in 2023. “Extreme weather events put that at risk.” The rise is expected to go up by another foot by 2050.
“We ignore these threats at the peril of our national security and at great risk to those in uniform who must operate, on orders of our president, the sea lifts, the air lifts and other missions to alleviate humanitarian suffering or sovereign instability in remote regions of the world.” Warner testified in 2009.
His words continue to ring true, no matter what is tweeted, deleted or willfully ignored.
Chelsea Henderson is the author of “Glacial: The Inside Story of Climate Politics” and serves as the director of editorial content at republicEn.org, a project of the George Mason University Center for Climate Change Communication. Banner photo: Aircraft carriers at Naval Station Norfolk (Mass Communication Specialist 2nd Class Ernest R. Scott, Public domain, via Wikimedia Commons).
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The military has a mnemonic used to help commanders remember and prioritize the key factors to analyze during the planning phase of any operation, METT-TC: Mission, Enemy, Terrain and Weather, Troops and Fire Support Available, Time Available, and Civilian Considerations. Even with 21st Century technology, all weather fighters, thermal imaging systems etc., TERRAIN & WEATHER still dictate operations. Failure to account for the weather at the strategic, operational, & tactical levels will lead to mission failure. Whether it’s Parris Island become untenable for Marine Basic Training due to the rise of sea levels or flooding on the Missouri river shutting down Offutt AFB failure to account for the weather will lead to mission failure.
Even Majors from the MNNG pretending to be the SECDEF should remember METT-TC